var fibonacci = function (n) {
    if (typeof n !== 'number') {
        throw new Error('n should be a Number')
    }
    if (n < 0) {
        throw new Error('n should >= 0')
    }
    if (n > 10) {
        throw new Error('n should <= 10')
    }
    if (n === 0) {
        return 0
    }
    if (n === 1) {
        return 1
    }
    return fibonacci(n - 1) + fibonacci(n - 2)
}

if (require.main === module) {
    var n = Number(process.argv[2])
    console.log('fibonacci(' + n + ') is', fibonacci(n))
}

exports.fibonacci = fibonacci
